Sinclair ZX80 / ZX81 / Z88 Forums

I am not sure for the Lambda, but the Sinclair ZX80 and ZX81 have the dataline (databus) not directly wired from the CPU but from the RAMs. There are resistors decoupling the (external) RAM content when the ULA becomes active during video display and takes the opcode from the (external) RAM and ser...

Picked up a second working Lambda so I've decided to be a bit daring and mod it. One of the changes I want to do is to bring the missing CPU lines out to the edge connector. The question is, electrically, what is the best way to handle the lines? My inclination is to run them directly from CPU socke...

PM'd... Definitely want one!

Just when You thought there was none left , up pops Ian with 60 of the buggers!! :lol: http://www.ebay.co.uk/itm/Sinclair-ZX81-ULA-Ferranti-ULA-2C210E-Fix-Those-ZX81-Video-Display-Problems-/261252926070?pt=UK_VintageComputing_RL&hash=item3cd3e34a76 Lol... Rats! everything I'm away I miss the good s...

PokeMon wrote:I think the extension Lambda Multirom should work with my 32k RAM extension with following change:
Pin 4 of the 74HCT32 (IC6) should be connected to Vcc (+5V), Pin 14 of IC6.

Hmm... out of curiosity, sans the multirom, would your 32k extension work on a stock Lambda?

-John-

Mine came with a monster 12V 1.8A combination transformer and cosmic ray deflector. That scared me a little, so I substituted a 9V 1A transformerless unit. The Lambda seems happy enough to be on the same diet as a ZX81. If you're using a RAM pack I'd guess at 800ma optimal, but 500ma may suffice. I...

I just picked up a Lambda 8300, It's a tad incomplete, and as I'd rather not destroying it the first day out, does anyone know: What is the DC voltage & amperage in? I've seen it listed between 10.8V 500ma and 12V Can I use a standard ZX-81 16k RAM pack? Can I just jumper the missing expansion bus l...

...A little late once again, but if it helps I'd be interested in a couple boards as well.

I can see where using web forums on a smart phone would be harder, but as far as tablets go I've been using my 7" & 10" and never had an issue. In fact, because it's a very clean design, I've found this site to be one of the better ones. Personally, I always have to wonder that the catch on these "F...

The CMOS chips are faster and better IMHO so I think you've done the right thing! You're very right! The 27C128's showed up today and they burned without a problem. I don't know if you are aware of this, but the older NMOS EPROMs (like some 27128 chips) need a programming voltage of 21V. More moder...